Our overall objectives are to develop new analytical/clinical reaction rate methodology that will provide greater selectivity, sensitivity, speed and accuracy for the determination of a wide range of constituents in blood serum, urine, and other biological samples. Our past studies indicate that mechanistic studies and optimization of parameters inherent in rate procedures can be accomplished efficiently with our computer-controlled automated reaction-rate analyzers. The reaction-rate computer-controlled analyzers are to be used in both an automated investigative mode to study basic chemical reactions involved in development of analytical procedures for specific constituents, and also in a high-speed routine analytical mode for testing newly-developed methods with large numbers of serum or urine samples. The instruments will be modified where necessary to utilize the most reliable chemical system. Kinetic reactions involving high-speed primary reactions will be developed where feasible so as to gain the advantages of selectivity, speed, and overall reliability. Methods will be investigated for creatinine, free and bound calcium, BUN, cholesterol, uric acid and other constituents in serum samples. Further work will also be done on a rate method for determination of corticosteroids. We believe that the research proposed here can lead to a better basic understanding of the analytical principles inherent in various reaction-rate methods and can provide improved measurement concepts, and thus lead to the development improved methodology for the clinical chemistry laboratory.